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56 lines
3.3 KiB
HTML
<p>There is an <code>n x n</code> <strong>0-indexed</strong> grid with some artifacts buried in it. You are given the integer <code>n</code> and a <strong>0-indexed </strong>2D integer array <code>artifacts</code> describing the positions of the rectangular artifacts where <code>artifacts[i] = [r1<sub>i</sub>, c1<sub>i</sub>, r2<sub>i</sub>, c2<sub>i</sub>]</code> denotes that the <code>i<sup>th</sup></code> artifact is buried in the subgrid where:</p>
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<ul>
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<li><code>(r1<sub>i</sub>, c1<sub>i</sub>)</code> is the coordinate of the <strong>top-left</strong> cell of the <code>i<sup>th</sup></code> artifact and</li>
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<li><code>(r2<sub>i</sub>, c2<sub>i</sub>)</code> is the coordinate of the <strong>bottom-right</strong> cell of the <code>i<sup>th</sup></code> artifact.</li>
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</ul>
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<p>You will excavate some cells of the grid and remove all the mud from them. If the cell has a part of an artifact buried underneath, it will be uncovered. If all the parts of an artifact are uncovered, you can extract it.</p>
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<p>Given a <strong>0-indexed</strong> 2D integer array <code>dig</code> where <code>dig[i] = [r<sub>i</sub>, c<sub>i</sub>]</code> indicates that you will excavate the cell <code>(r<sub>i</sub>, c<sub>i</sub>)</code>, return <em>the number of artifacts that you can extract</em>.</p>
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<p>The test cases are generated such that:</p>
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<ul>
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<li>No two artifacts overlap.</li>
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<li>Each artifact only covers at most <code>4</code> cells.</li>
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<li>The entries of <code>dig</code> are unique.</li>
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</ul>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2019/09/16/untitled-diagram.jpg" style="width: 216px; height: 216px;" />
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<pre>
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<strong>Input:</strong> n = 2, artifacts = [[0,0,0,0],[0,1,1,1]], dig = [[0,0],[0,1]]
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<strong>Output:</strong> 1
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<strong>Explanation:</strong>
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The different colors represent different artifacts. Excavated cells are labeled with a 'D' in the grid.
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There is 1 artifact that can be extracted, namely the red artifact.
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The blue artifact has one part in cell (1,1) which remains uncovered, so we cannot extract it.
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Thus, we return 1.
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</pre>
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<p><strong>Example 2:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2019/09/16/untitled-diagram-1.jpg" style="width: 216px; height: 216px;" />
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<pre>
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<strong>Input:</strong> n = 2, artifacts = [[0,0,0,0],[0,1,1,1]], dig = [[0,0],[0,1],[1,1]]
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<strong>Output:</strong> 2
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<strong>Explanation:</strong> Both the red and blue artifacts have all parts uncovered (labeled with a 'D') and can be extracted, so we return 2.
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 <= n <= 1000</code></li>
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<li><code>1 <= artifacts.length, dig.length <= min(n<sup>2</sup>, 10<sup>5</sup>)</code></li>
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<li><code>artifacts[i].length == 4</code></li>
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<li><code>dig[i].length == 2</code></li>
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<li><code>0 <= r1<sub>i</sub>, c1<sub>i</sub>, r2<sub>i</sub>, c2<sub>i</sub>, r<sub>i</sub>, c<sub>i</sub> <= n - 1</code></li>
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<li><code>r1<sub>i</sub> <= r2<sub>i</sub></code></li>
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<li><code>c1<sub>i</sub> <= c2<sub>i</sub></code></li>
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<li>No two artifacts will overlap.</li>
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<li>The number of cells covered by an artifact is <strong>at most</strong> <code>4</code>.</li>
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<li>The entries of <code>dig</code> are unique.</li>
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</ul>
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